Aspects of the present invention are directed to a method to characterize a laminate shape and to optimize chip packaging yield.
In chip manufacturing processes, chips are often formed of laminates that are layered upon one another and then bonded to form a package. For these processes to be optimized, the laminates selected for use should have shapes, warpage and/or coplanarity that conform to required predefined shapes, warpage and/or coplanarity since laminates that do not meet the requirements will not reliably fit together. In the case of laminates formed of organic materials (i.e., organic laminates) the predefined shape, warpage and/or coplanarity requirements are particularly important since organic laminates can relatively easily deform due to, for example, temperature dependent warpage during various stages.
Indeed, laminate warpage and, particularly, organic laminate warpage is known to impact assembly yield and performance in chip manufacturing processes and, therefore, efforts have been undertaken to address the issue. Typically, this is accomplished by the organic laminates being selected for use in chip manufacturing processes according to whether they meet a predetermined warpage specification value or, rather, a total laminate warpage value, which are absolute values that describe an amount of warpage exhibited by a particular laminate. A laminate that meets the warpage specification value or exhibits less warpage than the warpage specification value is selected for use and those that do not are discarded.
Unfortunately, the warpage specification value does not contain information about shape characteristics. Thus, it is possible that a laminate will satisfy the warpage specification value but have a shape that is still not suitable for an optimal laminate. That is, laminate selection using the warpage specification value or the total laminate warpage value only impacts the laminate yield and does not necessarily provide optimal laminates for assembly performance. On high end products, however, it is highly desirable to provide laminates with optimal characteristics to achieve highest first pass yield.